Tests intended for integration of a chemical loop in hydrocarbon conversion plants have been carried out.
Patent FR-2,850,156 describes the principle of chemical looping combustion, in a method dedicated to coal combustion.
Document US-2007/703,526 describes an improvement of the chemical loop in an integrated-combustion petroleum hydrocarbon conversion plant allowing CO2 capture, comprising a catalytic cracking reactor in the presence of fluidized catalysts and a catalyst regenerator through combustion of the coke settled on these particles. The regenerator is an oxygen support reduction reactor and it is supplied with solid fuel and/or petroleum residues comprising the coke-containing catalysts. The reduction reactor is associated with an oxidation reactor. The oxygen support circulates between the two reactors. The reduction reactor is a circulating fluidized bed that is fluidized by water vapour and/or recycled CO2 and/or SO2. This patent describes a method with a three-reactor layout. However, the oxidizing masses only circulate between two reactors and the goal is total combustion of the fuel.
Document US-2007/082,089 A2 describes a three-stage method highlighting the use of metallic oxides recirculation for hydrogen production. In a first reactor, total combustion of the fuel allows to produce CO2, H2O. Hydrogen production is performed by re-oxidizing the metallic oxide by means of water vapour. This method requires high vapour flow rates, and it is therefore necessary to heat and to evaporate a large amount of water prior to feeding it into the oxidation reactor, which leads to limitations as regards the energy balance.
Hydrogen production can be achieved through gasification: patent application 2008/036,902 describes for example a hydrocarbon gasification method that is implemented in a conventional layout with two reaction zones.
However, a problem that faces the person skilled in the art wanting to produce syngas (therefore hydrogen) by gasification is the kinetics of the reactions that take place in the gasification reactor, as well as the high reaction temperatures in the gasification reactor. The residence time required for the reactants is thus long. This directly affects the size of the plants and, more specifically, the size of the reactors involved, which leads to high investment costs.